A seal adapted for use with medical devices is provided. The medical device may be a lead having a distal tip adapted for implantation on or about the heart and for connection to a system for monitoring or stimulating cardiac activity. The lead assembly in one embodiment includes an atraumatic tip. A seal is provided within the lead tip assembly, which prevents or limits further entry of fluids through the lead tip. The lead may be a left ventricular lead with a hemostasis mechanism provided therewithin.